PPAR‐γ agonist pioglitazone alleviates inflammatory response induced by lipopolysaccharides in osteoblast cells

Abstract

Osteomyelitis is an acute or chronic inflammatory bone disease with a high disability rate. As an anti‐inflammatory factor, peroxisome proliferator activated receptor‐γ (PPAR‐γ) is not only implicated in a variety of inflammatory responses but also regulates osteoblast differentiation and bone mass. However, the role of PPAR‐γ in osteomyelitis is not fully understood. In the present study, we demonstrated that PPAR‐γ showed a lower expression level in infected bone tissue of osteomyelitis patients as compared with uninfected bone tissue from nonosteomyelitis patients with fracture of the hip. We applied lipopolysaccharides (LPSs) in MC3T3‐E1 osteoblast precursor cell line as an in vitro model for osteomyelitis. LPS treatment increased osteomyelitis‐associated inflammatory cytokines such as interleukin‐6 (IL‐6) and tumor necrosis factor‐α (TNF‐α), whereas PPAR‐γ levels and cell viability in MC3T3‐E1 cells were suppressed. PPAR‐γ antagonist GW9662 further enhanced IL‐6 and TNF‐α levels, and decreased cell viability in the presence of LPS treatment. In contrast, PPAR‐γ agonist pioglitazone antagonized the effect of LPS treatment in MC3T3‐E1 cells. These findings suggest that PPAR‐γ downregulation is associated with the inflammation and progression of osteomyelitis, and PPAR‐γ agonist could serve as a therapeutic strategy to attenuate inflammatory responses. This study provides novel insights into the physiopathogenesis of osteomyelitis and future study is required to validate the findings in animal model and uncover the molecular mechanism of PPAR‐γ‐dependent anti‐inflammation in osteoblasts.

PPARγ, NF-κB and the UPR pathway as new molecular targets in the anti-inflammatory actions of NSAIDs: Novel applications in cancers and central nervous system diseases?

“…Stimulation of PPARγ antagonizes the activity of NF-κB and consequently inhibits the formation of proinflammatory cytokines. 50,51 There are numerous natural PPARγ ligands, including polyunsaturated fatty acids, e.g., linoleic acid, docosahexaenoic acid, exogenous agonists such as flavonoids 52 (e.g., curcumin) and drugs such as glitazones, 53,54 and NSAIDs 43 that are responsible for an anti-inflammatory effect. Several members of the heterogenous nonsteroidal anti-inflammatory family of drugs have been described as ligands for PPARγ according to their affinities and activity for PPARγ.…”